3,972 research outputs found
Projectors and seed conformal blocks for traceless mixed-symmetry tensors
In this paper we derive the projectors to all irreducible SO(d)
representations (traceless mixed-symmetry tensors) that appear in the partial
wave decomposition of a conformal correlator of four stress-tensors in d
dimensions. These projectors are given in a closed form for arbitrary length
of the first row of the Young diagram. The appearance of Gegenbauer
polynomials leads directly to recursion relations in for seed conformal
blocks. Further results include a differential operator that generates the
projectors to traceless mixed-symmetry tensors and the general normalization
constant of the shadow operator.Comment: 49 pages, 1 Mathematica notebook, many figures, v2: add reference
Radial expansion for spinning conformal blocks
This paper develops a method to compute any bosonic conformal block as a
series expansion in the optimal radial coordinate introduced by Hogervorst and
Rychkov. The method reduces to the known result when the external operators are
all the same scalar operator, but it allows to compute conformal blocks for
external operators with spin. Moreover, we explain how to write closed form
recursion relations for the coefficients of the expansions. We study three
examples of four point functions in detail: one vector and three scalars; two
vectors and two scalars; two spin 2 tensors and two scalars. Finally, for the
case of two external vectors, we also provide a more efficient way to generate
the series expansion using the analytic structure of the blocks as a function
of the scaling dimension of the exchanged operator.Comment: 42 pages, 17 figures, 7 Mathematica files, v2: minor changes in the
text, typos correcte
Topography-based flow-directional roughness: potential and challenges
Abstract. Surface texture analysis applied to high-resolution digital terrain models (HRDTMs) is a promising approach for extracting useful fine-scale morphological information. Surface roughness, considered here as a synonym of surface texture, can have a discriminant role in the detection of different geomorphic processes and factors. Very often, the local morphology presents, at different scales, anisotropic characteristics that could be taken into account when calculating or measuring surface roughness. The high morphological detail of HRDTMs permits the description of different aspects of surface roughness, beyond an evaluation limited to isotropic measures of surface roughness. The generalization of the concept of roughness implies the need to refer to a family of specific roughness indices capable of capturing specific multiscale and anisotropic aspects of surface morphology. An interesting set of roughness indices is represented by directional measures of roughness that can be meaningful in the context of analyzed and modeled flow processes. Accordingly, we test the application of a flow-oriented directional measure of roughness based on the geostatistical bivariate index MAD (median of absolute directional differences), which is computed considering surface gravity-driven flow direction. MAD is derived from a modification of a variogram and is specifically designed for the geomorphometric analysis of HRDTMs. The presented approach shows the potential impact of considering directionality in the calculation of roughness indices. The results demonstrate that the use of flow-directional roughness can improve geomorphometric modeling (e.g., sediment connectivity and surface texture modeling) and the interpretation of landscape morphology
Global digital elevation models for terrain morphology analysis in mountain environments: insights on Copernicus GLO-30 and ALOS AW3D30 for a large Alpine area
This study focuses on the quality evaluation of two of the best 1 arc-second public global digital elevation models (DEMs), Copernicus GLO-30 DEM and ALOS AW3D30 DSM, from the perspective of their capability to represent the terrain fine-scale morphology of a complex alpine landscape, located in the Italian Trentino Province. The analysis is performed on an area of 6210 km(2), considering a reference DEM derived from a high resolution and accurate airborne Lidar survey. The quality assessment goes beyond a conventional approach based on elevation differences statistics, computed on a pixels-by-pixel basis. An ad hoc approach for evaluating the capability to represent fine-scale morphology, including surface roughness, is adopted. Moreover, the quality analysis is performed considering the influence of local morphology and of the different land covers. The findings show that although the two global DEMs have comparable overall quality, their relative performances change according to local landscape characteristics. Copernicus DEM performance is on average better than ALOS in correspondence of urbanized areas as well as in areas without vegetation cover, with gentle slopes and relatively low short-range roughness. Meanwhile, ALOS DEM performance is slightly better than Copernicus in rougher terrain and steeper slopes. In general, both DEMs have poor performances in steep slopes, with a limited capability to describe fine-scale morphology. The adoption of these global DEMs for terrain analysis and modelling of earth surface processes should be performed carefully, considering the impact of different land covers and of local morphology, including surface roughness
Gravitational Matter Creation, Multi-fluid Cosmology and Kinetic Theory
A macroscopic and kinetic relativistic description for a decoupled
multi-fluid cosmology endowed with gravitationally induced particle production
of all components is proposed. The temperature law for each decoupled particle
species is also kinetically derived. The present approach points to the
possibility of an exact (semi-classical) quantum-gravitational kinetic
treatment by incorporating back reaction effects for an arbitrary set of
dominant decoupled components. As an illustration we show that a cosmology
driven by creation of cold dark matter and baryons (without dark energy)
evolves like CDM. However, the complete physical emulation is broken
when photon creation is added to the mixture thereby pointing to a crucial test
in the future. The present analysis also open up a new window to investigate
the Supernova-CMB tension on the values of , as well as the tension
since creation of all components changes slightly the CMB results and the
expansion history both at early and late times. Finally, it is also argued that
cross-correlations between CMB temperature maps and the Sunyaev-Zeldovich
effect may provide a crucial and accurate test confronting extended CCDM and
CDM models.Comment: 16 pages, 1 figure, accepted for publication in European Physical
Journal
Mapping long-period soil resonances in the Kathmandu basin using microtremors
This study reports the geostatistical analysis of a set of 40 single-station horizontal-to-vertical spectral ratio (HVSR) passive seismic survey data collected in the Kathmandu basin (Nepal). The Kathmandu basin is characterized by a heterogeneous sedimentary cover and by a complex geo-structural setting, inducing a high spatial variability of the bedrock depth. Due to the complex geological setting, the interpretation and analysis of soil resonance periods derived from the HVSR surveys is challenging, both from the perspective of bedrock depth estimation as well as of seismic-site effects characterization. To exploit the available information, the HVSR data are analyzed by means of a geostatistical approach. First, the spatial continuity structure of HVSR data is investigated and interpreted taking into consideration the geological setting and available stratigraphic and seismic information. Then, the exploitation of potential auxiliary variables, based on surface morphology and distance from outcropping bedrock, is evaluated. Finally, the mapping of HVSR resonance periods, together with the evaluation of interpolation uncertainty, is obtained by means of kriging with external drift interpolation. This work contributes to the characterization of local seismic response of the Kathmandu basin. The resulting map of soil resonance periods is compatible with the results of preceding studies and it is characterized by a high spatial variability, even in areas with a deep bedrock and long resonance periods
Response of microchannel plates to single particles and to electromagnetic showers
We report on the response of microchannel plates (MCPs) to single
relativistic particles and to electromagnetic showers. Particle detection by
means of secondary emission of electrons at the MCP surface has long been
proposed and is used extensively in ion time-of-flight mass spectrometers. What
has not been investigated in depth is their use to detect the ionizing
component of showers. The time resolution of MCPs exceeds anything that has
been previously used in calorimeters and, if exploited effectively, could aid
in the event reconstruction at high luminosity colliders. Several prototypes of
photodetectors with the amplification stage based on MCPs were exposed to
cosmic rays and to 491 MeV electrons at the INFN-LNF Beam-Test Facility. The
time resolution and the efficiency of the MCPs are measured as a function of
the particle multiplicity, and the results used to model the response to
high-energy showers.Comment: Paper submitted to NIM
Desire thinking as a predictor of drinking status following treatment for alcohol use disorder: A prospective study
© 2019 Elsevier Ltd Research has indicated that craving is one of the strongest predictors of treatment outcome and relapse in Alcohol Use Disorders (AUD) but there is little consensus on the factors that may influence its activation and escalation. Research has also shown that desire thinking is an important cognitive process which may exacerbate craving in problem drinkers. The aim of present study was to explore, for the first time, the role of desire thinking in prospectively predicting relapse, craving and binge drinking in patients receiving treatment for AUD. One hundred and thirty-five patients admitted to two rehabilitation centres and two outpatient services for addiction and mental health problems were administered baseline, treatment completion and three months follow-up measures of anxiety and depression, AUD severity, binge drinking frequency, craving and desire thinking. Results indicated that the verbal perseveration component of desire thinking at treatment completion was the only significant predictor of relapse at follow-up over and above baseline AUD severity and binge drinking frequency. Furthermore, the imaginal prefiguration component of desire thinking and craving levels at treatment completion were found to predict craving levels at follow-up independently of AUD severity and binge drinking frequency at baseline. Finally, both the imaginal prefiguration and verbal perseveration components of desire thinking at treatment completion were found to be the only predictors of binge drinking frequency at follow-up independently of AUD severity and binge drinking frequency at baseline. Treatments for AUD should aim to reduce desire thinking in people to enhance clinical outcomes and reduce relapse risk
Lidocaine for systemic sclerosis: a double-blind randomized clinical trial
Background: Systemic sclerosis (scleroderma; SSc) is an orphan disease with the highest case-specific mortality of any connective-tissue disease. Excessive collagen deposit in affected tissues is a key for the disease's pathogenesis and comprises most of the clinical manifestations. Lidocaine seems to be an alternative treatment for scleroderma considering that: a) the patient's having excessive collagen deposits in tissues affected by scleroderma; b) the patient's demonstrating increased activity of the enzyme prolyl hydroxylase, an essential enzyme for the biosynthesis of collagen; and c) lidocaine's reducing the activity of prolyl hydroxylase. the aim of this study was to evaluate the efficacy and safety of lidocaine in treating scleroderma.Methods: A randomized double-blind clinical trial included 24 patients with scleroderma randomized to receive lidocaine or placebo intravenously in three cycles of ten days each, with a one-month interval between them. Outcomes: cutaneous (modified Rodnan skin score), oesophageal (manometry) and microvascular improvement (nailfold capillaroscopy); improvement in subjective self-assessment and in quality of life (HAQ).Results: There was no statistically significant difference between the groups for any outcome after the treatment and after 6-months follow-up. Improvement in modified Rodnan skin score occurred in 66.7% and 50% of placebo and lidocaine group, respectively (p = 0.408). Both groups showed an improvement in subjective self-assessment, with no difference between them.Conclusions: Despite the findings of a previous cohort study favouring the use of lidocaine, this study demonstrated that lidocaine at this dosage and means of administration showed a lack of efficacy for treating scleroderma despite the absence of significant adverse effects. However, further similar clinical trials are needed to evaluate the efficacy of lidocaine when administered in different dosages and by other means.Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Universidade Federal de São Paulo, Escola Paulista Med UNIFESP EPM, Brazilian Cochrane Ctr, São Paulo, BrazilUniversidade Federal de São Paulo, Escola Paulista Med UNIFESP EPM, Discipline Emergency Med & Evidence Based Med, São Paulo, BrazilUniversidade Federal de São Paulo, Escola Paulista Med UNIFESP EPM, Discipline Rheumatol, São Paulo, BrazilUniv Santo Amaro, Discipline Rheumatol, São Paulo, BrazilUniversidade Federal de São Paulo, Escola Paulista Med UNIFESP EPM, Brazilian Cochrane Ctr, São Paulo, BrazilUniversidade Federal de São Paulo, Escola Paulista Med UNIFESP EPM, Discipline Emergency Med & Evidence Based Med, São Paulo, BrazilUniversidade Federal de São Paulo, Escola Paulista Med UNIFESP EPM, Discipline Rheumatol, São Paulo, BrazilFAPESP: 01-13895-9Web of Scienc
Acute kidney injury and acute kidney disease in high-dose cisplatin-treated head and neck cancer
Background: In locally advanced head and neck squamous cell carcinoma (LA-SCCHN) at least 200mg/m2 (standard dose 300 mg/m2) of cisplatin concomitant with radiotherapy represents the standard of care, both in postoperative and conservative settings. Nevertheless, high dose administration every 3 weeks is often replaced with low dose weekly cisplatin to avoid toxicities like kidney injury, though often failing to reach the therapeutic dose. Our aim was to investigate the incidence of renal impairment in the real-life setting, integrating high dose cisplatin with adequate supportive therapy, and to explore both Acute Kidney Injury (AKI) and Acute Kidney Disease (AKD), a recently described clinical renal syndrome that encompasses functional alterations of the kidney lasting fewer than 3 months. Methods: One hundred and nine consecutive patients affected by LA-SCCHN and treated with at least a cumulative dosage of 200 mg/m2 of cisplatin concomitant with radiotherapy were enrolled in this prospective observational study. Results: AKI was reported in 12.8% of patients, 50% of whom were stage 1 (KDIGO criteria), while 25.7% of the cohort developed AKD. Patients with baseline estimated Glomerular Filtration Rate (eGFR) < 90 ml/min showed a higher incidence of AKD (36.2% vs 17.7%). Hypertension, baseline eGFR, and therapy with Renin-angiotensin-aldosterone system inhibitors proved to be significant factors associated with both AKI and AKD. Conclusion: AKI and AKD are not rare complications of high-dose cisplatin, but an appropriate prevention strategy and accurate monitoring of patients during treatment could lead to a reduction of the burden of these conditions
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